偏侧咀嚼对正畸牙移动影响的实验研究

Influence of unilateral chewing on orthodontic tooth movement

目的通过建立偏侧咀嚼大鼠模型,探讨偏侧咀嚼对正畸牙移动过程的影响。方法选择30只6～8周龄,(250±10)g,雄性SD大鼠,随机分为实验组与对照组,每组各15只。通过拔除实验组大鼠右下颌所有磨牙使右上颌第一磨牙丧失咬合接触建立大鼠偏侧咀嚼动物模型,同时,在两组大鼠双侧上颌切牙和第一磨牙间放置镍钛拉簧,初始力值为50g,近中移动磨牙。分别于第0、3、7、10、14天测量大鼠上颌第一磨牙近中移动的距离并通过HE染色观察大鼠上颌第一磨牙牙周组织形态学变化。结果各时间点代偿性咀嚼增强侧牙移动速率均小于对照组(P<0.05),牙周组织变化与对照组相似;失咬合侧牙移动速率大于对照组(P<0.05),牙周组织出现退行性改变;但三种咬合状态下牙齿移动速率曲线均表现为瞬时运动、迟滞期及后期移动三个阶段。结论动物实验证实偏侧咀嚼引起正畸牙牙周组织发生相应改变最终影响牙移动速率,但无论牙移动速率快慢,牙移动均符合正畸性牙移动的一般规律。

Objective To investigate the influence of unilateral chewing on orthodontic tooth movement and the periodontal tissue. Methods Thirty male rats, 6 - 8 weeks old and weighed （250 ± 10） g, were divided into experimental group and control group equally and randomly. The animals, in experimental group, were induced by extracting the right mandibular molars and the left maxillary molars were served as increased bite force models while the right maxillary molars were served as decreased ones. The animals, in control group, were treated non - extraction. The maxillary first molar was moved mesially with a force of 50g. Tooth movements were measured at 0, 3, 7, 10, 14 days. Then the animals were killed and histologic examination was used to evaluate the maxillary first molar and its periodontal tissues. Results Orthodontic tooth movement on the side of increased bite force was slower than that of the controls, and the tooth movement on the side of decreased bite force was faster. However, molar movement followed classical tooth movement curve. The periodontal tissue on the side of increased bite force revealed the similar changes to that of controls, while the periodontal tissue on the side of decreased bite force showed atrophy. Conclusion Unilateral chewing influenced the velocity of orthodontic tooth movement but the classical tooth movement curve was kept unchangingly.